47 - Build Your Own Mortising Machine , страница 26

IN THE SHOP

Brush

upon the

Basics

One of the secrets to ending up with a smooth, even finish is selecting the right brush and using a few simple techniques.

I often use "throwaway" foam brushes to apply a finish, but I'm not always satisfied with the results. Would a bristle brush work better? Also, are there any special brush techniques I can use that will ensure good results?

Frank Haynes Davenport, Iowa

¥ M "W

1 ft f hen it comes to ease of use, If If a foam brush is hard to beat. They cost next to nothing. But I've had mixed results with them.

So when applying a finish to a special project, I use a bristle brush. There are several advantages to using a quality bristle brush.

First, it holds plenty of finish, so you aren't constantly dipping it back in the container to replenish the brush. (It also isn't as likely to drip.) Second, the bristles allow the finish to flow out smoothly and evenly with very few brush marks.

SELECTING A BRUSH. So how do you go about selecting a quality brush? After all, if you walk down the paint aisle at the local home center, there are hundreds of brushes to choose from.

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anchors setting

ANATOMY to handle

First of all, any brush is going to have the same basic parts, see drawing below. But it's the bristles in the brush that make the difference in the quality of the finish.

TYPES OF BRISTLES

You'll find two types of bristles: natural and synthetic, see photos above.

NATURAL BRISTLES. Like their name implies, natural bristle brushes are made from animal hair. As a rule, I use a natural bristle brush to apply a finish like varnish or shellac. These bristles seem to hold more finish. And in general, I get better results.

The only exception is when I'm applying a water-based finish. With this type of finish, the bristles absorb too much water, and they get soft and limp — almost as if they're having a "bad hair" day. This makes it difficult to control the amount of finish I brush onto the workpiece.

SYNTHETIC BRISTLES. So when working with water-based finishes, I use a brush that has synthetic bristles. These bristles are made of

Bristles wick up, hold, and release finish

plastic, so they absorb very little water and won't deform during use.

BRISTLE TIPS

Another consideration when choosing a brush is the tips of the bristles.

FEEL FOR SOFTNESS. If your eyesight is like mine, it will be impossible to actually see the tips of the bristles. But you can feel them. Remove the paper "keeper" from the brush and fan the bristles against your hand.

STIFF BRISTLES. If they feel stiff, it's probably because the tips of the bristles are cut square, see detail 'a' below. These bristles are okay for' general painting jobs, but they make it difficult to brush a smooth finish.

SUPPLE BRISTLES. If the brush has soft, supple bristles, it's a good indication that the bristles are either tapered or, better yet, "flagged" at the ends, see detail 'a.' (This is one time

Handle shaped for comfortable grip

2RISTLETIPS

SQUARE

TAPERED FLAGGED t

Divider creates reservoir Reservoir for finish holds finish

Epoxy setting binds bristles and divider together

b.

BRUSH SHAPE

CHISEL-EDGE BRUSH

SQUARE-EDGE BRUSH

26 ShopNotes

No. 47

A

Natural Bristles

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Bristles